News & Discussion: Public Transport Contracts, Service & Policy

[OlympusAnt]

Easily the most dangerous crossing in the state and should be an ultra high priority

[bits]

Do you get "interesting" effects on a freight train if the front and back are on hills, but the middle is in a hole? Can the locomotives exert enough pulling power to lift the middle of the train enough to derail or damage it? That could be a concern with a relatively short underpass, too.

A ditch going south can be as long as needed, there is km's to play with.

All comes to if it is cheaper to dig a ditch vs build a 3 track(1 being freight rail) long bridge. And just what kind of grade would be acceptable.

I did some basic reading on acceptable grade on railways.
It seems 2% grade is acceptable.
http://www.modelbuildings.org/free-trac ... lator.html

If the ditch was 4m deep and had 200m run it would be a 2% grade, eg right on the edge of widely acceptable.
4m over 300m is 1.33%
I suggested 2m over 300m which is 0.67%.


Move the station slightly south and build stairs from Park Tce to both platforms like at Mawson Lakes.
You could also have a general pedestrian underpass to connect both sides of Park Tce.
Reduce noise due to ditch.
Better visually than a bridge in the air.
It would be win, win, win. All the idea needs is money.

[ml69]

Do you get "interesting" effects on a freight train if the front and back are on hills, but the middle is in a hole? Can the locomotives exert enough pulling power to lift the middle of the train enough to derail or damage it? That could be a concern with a relatively short underpass, too.

A ditch going south can be as long as needed, there is km's to play with.

All comes to if it is cheaper to dig a ditch vs build a 3 track(1 being freight rail) long bridge. And just what kind of grade would be acceptable.

I did some basic reading on acceptable grade on railways.
It seems 2% grade is acceptable.
http://www.modelbuildings.org/free-trac ... lator.html

If the ditch was 4m deep and had 200m run it would be a 2% grade, eg right on the edge of widely acceptable.
4m over 300m is 1.33%
I suggested 2m over 300m which is 0.67%.


Move the station slightly south and build stairs from Park Tce to both platforms like at Mawson Lakes.
You could also have a general pedestrian underpass to connect both sides of Park Tce.
Reduce noise due to ditch.
Better visually than a bridge in the air.
It would be win, win, win. All the idea needs is money.

Is Park Tce Salisbury higher priority or Oaklands crossing? I have no idea, don't live near either ...

[[Shuz]]

Salisbury is higher priority in terms of safety but Oaklands wins votes. Such is the fusion between politics and infrastructure planning.

[Aidan]

Considering Salisbury has the emergency escape lanes and Oaklands doesn't, I'd rate Oaklands much higher priority in terms of safety. Oaklands also rates very highly for capacity, as does Hove.

However the Salisbury crossing is on a minor road, so it should be acceptable to use deviations and steep gradients to divert the road under or over the railway.

[[Shuz]]

Park Terrace is a minor road?

Get your head out the sand, Aidan.

[crawf]

Not to mention Salisbury is one of the busiest interchanges in the metro area, aswell as the main transportation hub for the northern suburbs.

Though it's probably the most run down, and is in desperate need of a major multi-million dollar overhaul. Therefore any plans to eliminate the Park Tce crossing, needs to include the interchange.

[Aidan]

Park Terrace is a minor road?

OK, I admit that was a bit of an exaggeration. But it's not an arterial like Diagonal Road, and the Salisbury Highway extension took away most of the traffic it used to carry.

My point is it could easily accommodate the sort of curves and gradients unthinkable on an arterial road.

As for the bus interchange, that could easily be fixed by reverting to something more like its original layout (from before level crossing safety considerations forced them to reverse the direction of the buses). There's no good reason to knock it all down and start again.

The most important consideration is to keep the trains running during construction. Any "solution" which fails to do this is worse than doing nothing.

[Goodsy]

What about an elevated station with a bus terminal underneath it

[Torrens_5022]

Oaklands should be the first crossing to go then Torrens Rd Ovingham then Brighton Rd Hove. Park Tce Salisbury is a high priority - probably next in line but it has an alternative detour.
Top crossings for removal - Diagonal / Morphett Rds Oaklands, Torrens Rd Ovingham, Brighton Rd Hove, Park Tce Salisbury (all will need a rebuilt station) then not in any order Marion / Cross Rds Plympton, Kings Rd Salisbury Downs / Parafield Gardens - new elevated station (remove Greenfields at same time). The Grange line crossing on Port Road will need to go if Grange / West Lakes get trams, there's probably heaps more I can't think of

[Aidan]

Regarding bits's comments about gradients, the maximum gradient on ARTC's line north of Islington is one in 150. Having steeper gradients would increase the cost of running interstate trains, so must be avoided. Plus an elevated or sunken station would would require three elevated or sunken tracks to be constructed alongside the existing tracks — unless the plan is to just grade separate the suburban tracks and retain the level crossing in the standard gauge line

[SBD]

Selected traffic volumes on roads with level crossings from https://www.dpti.sa.gov.au/traffic_volumes - annual average daily traffic estimates for 2-way flows produced in 2015:

• Park Terrace Salisbury 18,600
• Kings Road 27,800
• Torrens Road 24,000
• Diagonal Road 41,800
• Brighton Road: 36,600
• Cross Road 19,600-25,100 - doesn't seem to have a number for the crossing, that's Cross Road either side of the bridge
• Park Terrace, Brompton 49,300 (to be replaced as part of Torrens Junction)
• South Road 36,100 (now replaced by bridge)

I don't know if anyone has data about average or peak wait times, or how peaky the traffic flow is at any of these places. Daily average flows might not be as significant as hourly peak flows.

[bits]

Daily average flows might not be as significant as hourly peak flows.

Complex surrounding intersections and pedestrian usage likely also count.

Eg
1)Diagonal Rd many cars, extremely close to signalized major intersections and very close to a major pedestrian hub(I would regard its pedestrian problem lower than Salisbury however). Lengthy consistent delays to motorists due to complex intersection arrangement.
2)Park Terrace Salisbury few cars but the road is extremely close to 2 signalized major intersections, a bus interchange, business driveways and is right in a major pedestrian hub. Site of the most major catastrophic accident caused by train in the state/country? Lengthy consistent delays to motorists due to complex intersection arrangement.
3)Brighton Rd many cars, not close to signalized or major intersections, not in a pedestrian hub, only a few minor drive ways to deal with.
4)Torrens Rd many cars, close to a single signalized T-intersection, not in a pedestrian hub, only a few minor driveways to deal with.
5)Kings Rd has a bunch of cars, but the road is dead straight, high speed and with no close intersections or drive ways and basically no pedestrians other than what the train itself created.


PS surely Cross Rd will be resolved within the North-South Motorway project.

[ChillyPhilly]

Here's the report on the Park Terrace crash.

https://www.atsb.gov.au/media/1996510/r ... 02_001.pdf

[[Shuz]]

Alternative solution to Park Terrace grade seperation is to do a half / half job, where the line is partially elevated and the road partially lowered (similar to Outer Harbour line / North South Motorway grade seperation.

This would minimise the gradients required for both freight and passenger lines going overhead Park Terrace and possibly avoid having to rebuild the Salisbury Highway rail bridge. However, it would also mean that North Lane be made a dead end and the Eureka Tavern loses its site access from Park Terrace.

Construction time could theoretically take 3-4 weeks if works undertaken 24/7.

Also benefit would be that the transfer between elevated Salisbury station to bus interchange is more user friendly, potentially no lifts required and steps / gentle incline of disability access down to bus interchange as difference between levels would be only 3 or 4 metres, instead of the full 8-10 metres required for a full elevated station.